Hybrid electric presses have set a new heavyweight milestone with a new 3850-ton model announced at the Tokyo IPF show by Mitsubishi Heavy Industries, known here as MHI Injection Molding Machinery Inc., Bensenville, Ill. A 1600-tonner was the largest previously offered by this company. Mitsubishi is considering introducing models in the 2000-ton range late in 2006.
The new 3500em two-platen model features four direct-drive AC servomotors for injection, and another single servo drive for plasticating. The low-speed/high-torque direct-drive motors used for injection were developed by Mitsubishi and reportedly deliver a faster response (50 millisec) than a high-speed hydraulic servo. Fanuc built the other AC servos used on the press. These include two belt-drive motors for clamp traverse movements, two servos that drive a hydraulic system that builds clamp tonnage on the tiebars, two more that actuate the split nuts on the tierods, and one for ejection. Company officials say this press can mold a 9.5-lb bumper fascia in 30 sec, and it has overall position accuracy of 0.01 mm or better.